The present disclosure relates generally to materials that can be used in photolithography processes such as immersion lithography. However, other applications may benefit from aspects of the disclosure and be within the scope of the disclosure.
Lithography is a mechanism by which a pattern on a mask is projected onto a substrate such as a semiconductor wafer. As feature sizes decrease, immersion lithography, in which the exposure procedure is performed with a liquid filling the space between the wafer and the lens, is often used. Using immersion lithography allows for higher numerical apertures (NA) than when using lenses in air, and therefore, provides for improved resolution. Further, immersion provides enhanced depth-of-focus (DOF) for printing smaller features.
Immersion lithography may use water or other suitable immersion exposure fluid in the space between the wafer and the lens. The immersion fluid can cause issues such as, droplets of fluid interfering with the exposure process. For example, at a high scanning speed, an immersion fluid drop and/or a resulting “bubble” may impact the image performance. The immersion fluid drop may also induce particles to the wafer surface. Furthermore, the immersion fluid drop may influence the photosensitive material chemical distribution in a resist layer, which may decrease the image pattern performance.